The present invention relates to a branched telephone system in which a plurality of telephones are connected to a single subscriber line or to single radio equipment and, more particularly, to a branched telephone system capable of automatically cancelling a priority set condition in which particular one of the plurality of telephones is usable.
In most of prior art branched telephone systems, two or more telephones are simply connected in parallel with no special control provided over them. In such a configuration, all the telephones share entirely the same functions and, therefore, it is impossible to give priority to the particular one of the plurality of telephones over the others or to positively invalidate the latter. For example, in a vehicle-mounted telephone system, two independent telephones may be connected to single radio equipment which is mounted on a vehicle and individually disposed in the vicinity of a front seat and a rear seat of the vehicle. It often occurs with such a vehicle-mounted telephone system that an occupant in the vehicle desires to invalidate one of the two telephones. In greater detail, the person, who wishes to originate a call on the particular one of the plurality of telephones near the rear sheet, may desire to keep the telephone number of the other party and the contents of communication from the driver.